Performing the glitch

First, the player must have a Q ◣ or 'M (FF), at least one Pokémon above it and two Pokémon below it, all in the party. The Pokémon below the Q ◣ or 'M (FF) will be the 'donor' to the Pokémon below it; that Pokémon will then be the donor to the Pokémon below it, etc. The Q ◣ or 'M (FF) will appear in the top slot where the deposited Pokémon was, but also stay in its original spot and be the donor to the Pokémon directly below it. Each Pokémon is now an 'unstable hybrid' of it and the Pokémon that was below it. An unstable hybrid cannot be traded to Pokémon Gold, Silver, or Crystal. An unstable hybrid displays the sprite, mini-sprite and type of the 'donor' Pokémon, and evolves in the same way as it. It has the species name (shown on the second page of the summary screen), learnset, TM/HM compatibility and effective type combination of the donor Pokémon. An unstable hybrid Pokémon has the color palette of the recipient, and those created with the Pokémon merge glitch have the recipient's nickname.

Stabilizing

To stabilize an unstable hybrid Pokémon, a Pokémon can be evolved (in the way the donor would), traded to Pokémon Stadium 2 (this makes both species bytes match the recipient), or deposited and withdrawn from Pokémon Day Care (this makes both species bytes match the recipient). Once stabilized, the Pokémon can be traded to the Generation II games.